The exocrine function of the pancreas is actually the major function of the pancreas and takes up much more of the pancreas' mass than its endocrine function. It secretes proteases to digest proteins and polypeptides, pancreatic lipase to digest fats and amylase to digest carbohydrates. The pancreas is the main source of enzymes for digesting fats (lipids) and proteins - the intestinal walls have enzymes that will digest polysaccharides. Pancreatic secretions contain bicarbonate ions and are alkaline in order to neutralize the acidic chyme that the stomach churns out.

Control of the exocrine function of the pancreas are via the enzymes gastrin, cholecystokinin and secretin, which are enzymes secreted by cells in the stomach and duodenum, in response to distension and/or food and which cause secretion of pancreatic juices.

The two major proteases the pancreas excretes are trypsinogen and chymotrypsinogen. These are inactivated forms of trypsin and chymotrypsin. Once released in the intestine, the enzyme enterokinase present in the intestinal mucosa activates trypsinogen by cleaving it to form trypsin. The free trypsin then cleaves the rest of the trypsinogen and chymotrypsinogen to their active forms.

In addition to these enzymes already mentioned above, the pancreas also secretes a bunch of other digestive enzymes to digest specific things including nuclear material (DNA).

The sweetbread, a gland connected with the intestine of nearly all vertebrates. It is usually elongated and light-colored, and its secretion, called the pancreatic juice, is discharged, often together with the bile, into the upper part of the intestines, and is a powerful aid in digestion. See Illust. of Digestive apparatus.